Biometric Camera Mount System

ABSTRACT

A system for reducing the substantially vertical extent of a wide-area biometric system and for reducing the cost and complexity of installation while maintaining high biometric performance, using a substantially horizontally configuration of cameras, preferably with an attention mechanism, and using a precision calibration system that can be used by an unskilled technician and that does not require an accurate site survey or additional materials or equipment.

CROSS-REFERENCE TO RELATED APPLICATIONS

This application claims benefit from provisional application 61/164528filed Mar. 30, 2009, which is hereby incorporated by reference in itsentirety.

BACKGROUND OF THE INVENTION

Biometrics is the science and technology of measuring and analyzingbiological data, such as the imagery of the face or iris. There are 3problems that need to be overcome with the acquisition of biometricdata: (i) ensuring that the biological data is within the field ofcoverage of one or more of the biometric sensors which is oftendifficult to control precisely since the sensors may be mounted indifferent ways for different deployments, and (ii) ensuring that thedata is acquired as uniformly as possible so that comparison of datafrom the same user across different time periods is facilitated, and(iii) ensuring that the user is looking in the vicinity of the camerasystems used in any face or iris recognition system

SUMMARY OF THE INVENTION

The invention comprises three primary elements: (i) a cameraconfiguration whereby two or more cameras are aligned substantiallyhorizontally while the field of coverage is substantially vertical, inorder to reduce vertical height of the biometric device, (ii) a pivotmechanism that allows the camera configuration to be moved in unison inorder to provide the same vertical field of coverage given differentdeployment-specific height and angle constraints imposed on the mountinglocation of the biometric device, and (iii) an attention mechanismcomprising a display showing video of a person walking towards thebiometric device.

BRIEF DESCRIPTION OF THE DRAWINGS

FIG. 1 shows prior art whereby multiple cameras are mounted in front ofa user at a fixed angle and at a fixed height such that the face of theperson is in the field of view of at least one of the cameras. FIG. 2shows a configuration where a biometric device is mounted above adoorway and covers a region of interest within the doorway. FIG. 3 showsa particular configuration of a biometric device mounted above a doorwaycomprising an attention mechanism, and three cameras mountedhorizontally covering a vertical region of interest. FIG. 4 shows aprofile view of a biometric system mounted above a doorway, showing howthe region of interest depends on the height H of the device and thetilt Theta of the device. FIG. 5 shows a profile view of a biometricsystem mounted above a doorway whereby the cameras are mounted on apivot the angle of which is adjusted by a calibration knob, such thatthe vertical region of interest of the biometric device can be adjustedon-site depending on deployment-specific constraints on the height andangle of the device.

DETAILED DESCRIPTION OF THE INVENTION

One existing approach to ensuring that the biological data is within thefield of coverage is shown in FIG. 1 (prior art). In this system calledSmart Gate (e.g.http://www.abc.net.au/science/news/stories/s1048494.htm), face imageryis acquired by one of 3 cameras mounted vertically in front of a user.The user is asked to stare straight forward at a kiosk, and the camerasare stacked vertically parallel to each other with a large verticalspacing so that the camera closest to the height of the user alwayscaptures a frontal view of the face. Ensuring a frontal view of the userfacilitates comparison of the same user at a different time period, andimproves overall system match performance.

FIG. 2 shows a different configuration for a biometric system. In thiscase, the biometric system has to be mounted between the top of adoorway and a ceiling (H1in FIG. 2) which is typically 8-12″. Ingeneral, the biometric system has to be mounted in a very small verticalspace between a lower obstruction and a higher obstruction.Unfortunately, the vertical region of interest of the system, H2, istypically much larger than the vertical space H1 that is available tomount the biometric system. H2is typically 24″ or more. Even if H1isgreater than H2such that the cameras in FIG. 1 could be raised above adoorway, then a problem still exists since if the user is asked to lookstraight ahead or at a fixed point, then a camera view will acquire avertically skewed, perspective view of the person's face or iris, whichmakes matching the biometric data much more difficult.

FIG. 3 shows how the problem has been addressed. First, the cameras aremounted horizontally in the gap H1 rather than vertically. Mounting thecameras horizontally reduces significantly the vertical space occupied,and each camera is tilted and panned carefully to cover a differentvertical portion of the region of interest as shown in FIG. 3 by thenumber of the camera and the number of the region of interest. Second,the horizontal spacing between the cameras is minimized as much asphysically possible. A preferred separation is 2″ or 4″. The approach ofmounting the cameras horizontally saves vertical space, but itpotentially introduces a new problem in that horizontally skewing of theimagery of the subject will occur, in addition to the vertical skewingdiscussed earlier which as discussed previously makes the matching ofthe biometric data much more difficult. By mounting the cameras with aclose horizontal separation however minimizes the degree of horizontalskewing. Thirdly, an attention-mechanism, such as a video screen showinglive video of the user as they use the system, is placed near thecameras. The user is then asked to look at the video screen. Users whoare short and are at the bottom of the region of interest will have tolook up at a greater tilt angle than users who are tall and are at thetop of the region of interest. The benefit of this approach is thatvertical skewing of the imagery introduced by the position of thecameras is cancelled out by the user tilting their head to the samevertical height as all the cameras.

Because the cameras are all at the same height, then the verticalskewing will be cancelled out equally in all camera views. If anattention mechanism at the camera cannot be applied due to the physicalconstraints of the system, then an alternative more complex solution tothis third step is a fore shortening compensation algorithm to removethe vertical skewing.

While this discussion has focused on allowing a substantially verticalregion of interest to be covered using a horizontal arrangement ofcameras, alternatively the same method could be used such that asubstantially horizontal region of interest is covered using a verticalarrangement of cameras. The cameras could also be pan/tilt/zoom cameras,either moved directly or by means of a mirror.

FIG. 4 shows a profile view of amount of a biometric system between aceiling and a doorway. There are two problems with such an installationcompared to the installation of a traditional biometric system. First,traditional biometric systems typically have carefully definedspecifications that define the precise height that the unit should bemounted above the floor. However, when mounting a system between aceiling and a doorway, the height of the doorway and the height of theceiling dictates the vertical positioning, H, of the system, and not theinstallation manual. Further, the heights of doorways and ceilings varysubstantially. This is very problematic since a biometric systemdesigned for a certain vertical region of interest to capture a range ofheights will not function properly if mounted at an unspecified height.Further, traditional biometric systems have typically acquired datawithin a small distance (approximately within 8-12″) so that any slightangle, theta, in the pitch of the device does not move the verticalregion of interest substantially. However, more recent biometric systemscan acquire data many feet away from the device, and therefore anyslight angle, theta, in the pitch of the device can move the verticalregion of interest substantially. The slight variations in pitch andheight of the device depend on the circumstances that arise duringactual installation, such as the flexing of the wall mounting points,and therefore cannot be calculated from site survey measurements withsufficient accuracy to allow adjustment at the factory. We havedeveloped a method that allows an unskilled installation technician toadjust a complex biometric system in a very short period of time,thereby minimizing installation time and cost.

FIG. 5 shows the solution we have developed. The cameras are all mountedon a single camera module that in turn is mounted on a horizontal pivot.A pivot push bar is attached to the camera module. A housing bar isattached to the case of the biometric system which in turn is attachedto the wall or other installation arrangement. A calibration knobcomprising a screw thread is screwed through the housing bar and pushesagainst the pivot push bar. The installation technician installs thebiometric unit without having to be concerned substantially with thepitch of the device, and only has to ensure that the device lies withina very broad height range (e.g. 6.5ft-12ft) which can be ascertainedfrom inaccurate and rapid site-survey analysis. The installationtechnician is then able to adjust the precise vertical region ofinterest by rotating the calibration knob. Rotating the calibration knobduring installation pushes the pivot push bar which in turns rotates thecamera module within the housing. The installation technician can adjustthe knob and then test performance at different heights in the region ofinterest. The use of the screwed thread as an adjustment mechanism hasthe benefit of (i) great precision in adjustment with a wide range oftravel (ii) allows the operator to make relative adjustments to allowiterative calibration (e.g. turn the knob one revolution, re-test thebiometric system, turn the knob a second revolution) without having toperform a difficult and error prone absolute calibration which mayrequire the participation of a second person which increases cost, orrequires additional calibration support materials such as target chartscarefully positioned, which take time to set up and are error prone.

1. A biometric system comprising two or more camera sensors with aregion of interest that is substantially vertical and with a physicalarrangement of camera sensors that is substantially horizontal.
 2. Thesystem in claim 1, whereby the cameras are substantially horizontal andclosely spaced.
 3. The system in claim 2, whereby there is an attentionmechanism substantially near the cameras.
 4. The system in claim 3,whereby the attention mechanism is a video monitor showing imagery ofthe user.
 5. An adjustable biometric system comprising: (i) one or morecameras, (ii) a camera housing module housing the cameras whereby atleast the vertical orientation of each camera are fixed relatively toeach other, (iii) a biometric housing module that contains the camerahousing module, (iv) a substantially horizontal pivot mount for thecamera housing, (v) An adjustment mechanism that allows adjustment of atleast the vertical orientation of the camera housing with respect to thebiometric housing.
 6. The system in claim 5 whereby the adjustmentmechanism is substantially a screw-thread.